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<title>if-test</title>
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<h1>if-test</h1>

<h2>Purpose</h2>

<p>
Branch to the given destination if the given two registers' values compare as
specified.
</p>
<p>
Note: The branch offset may not be 0. (A spin loop may be legally constructed
either by branching around a backward goto or by including a nop as a target
before the branch.) 
</p>

<h2>Details</h2>

<table class="instruc">
<thead>
<tr>
  <th>Op &amp; Format</th>
  <th>Mnemonic / Syntax</th>
  <th>Arguments</th>
</tr>
</thead>
<tbody>
<tr>
  <td>32..37 22t</td>
  <td>if-<i>test</i> vA, vB, +CCCC<br/>
    32: if-eq<br/>
    33: if-ne<br/>
    34: if-lt<br/>
    35: if-ge<br/>
    36: if-gt<br/>
    37: if-le<br/>
  </td>
  <td><code>A:</code> first register to test (4 bits)<br/>
    <code>B:</code> second register to test (4 bits)<br/>
    <code>C:</code> signed branch offset (16 bits)</td>
</tr>
</tbody>
</table>

<h2>Constraints</h2>

<ul>
  <li>
    A and B must be valid register indices for the current stack frame.
  </li>
  <li>
    Registers vA and vB must not contain a reference value.
  </li>
  <li>
    Registers vA and vB must not be part of a register pair.
  </li>
  <li>
    Registers vA and vB must not contain a floating point value (???).
  </li>
    C must of a signed offset that, when added to the PC of the instruction,
    points to a valid bytecode instruction inside the same method.
  </li> 
</ul>

<h2>Behavior</h2>

<ul>
  <li>
    The values of registers vA and vB are compared according to the &lt;test&gt;
    condition. Two results are possible:
    <ul>
      <li>
        The condition holds. The value of C is used as a signed offset to the
        address of the if-&lt;test&gt; instruction. Execution continues at the
        resulting address.
      </li>
      <li>
        The condition does not hold. Execution continues at the instruction
        following the if-&lt;test&gt; instruction.
      </li>
    </ul>
  </li>
</ul> 

<h2>Exceptions</h2>

<p>
None.
</p>

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